Temperature dependence of electric field-gradient induced birefringence (Buckingham effect) and molecular quadrupole moment of N2. Comparison of experiment and theory

Observations of electric field-gradient induced birefringence (the Buckingham effect) in gaseous N2 over a range of temperature (≈293–412 K) and pressure (up to ≈2000 kPa) are reported. Analysis of the data shows that the temperature-independent contribution to the effect is not negligible, and values of the molecular hyperpolarizability, B, and quadrupole moment, Θ, are derived. In the case of the quadrupole moment, the experimental value [Θ=(−4.97±0.16)×10−40 C m2] and a state-of-the-art ab initio value [Θ=(−4.93±0.03)×10−40 C m2] due to Halkier, Coriani and Jørgensen [Chem. Phys. Lett. 294 (1998) 292] are in excellent agreement.